1. Field of the Invention
The present invention relates to a nonvolatile semiconductor memory apparatus such as a flash memory and to a memory system incorporating such apparatus.
2. Description of the Related Art
There exist storage systems wherein management information is written to a nonvolatile memory apart from user data. The reliability of this type of system in the face of a possible power failure or similar irregularities is affected by how often management information is written inside. The writing of management information, meanwhile, proves to be an overhead during a data write operation and thus can affect system performance in that state. That means there exists a trade-off between system reliability and performance upon data write.
Generally, a given nonvolatile memory storage system has its management information written thereto always in the same manner according to an information management technique adopted by the system in question. Management information is written to the system as it operates at a limited level of performance so as to maintain a predetermined level of reliability.